Faster and more powerful computer components allow the design and construction of higher performance portable computing devices such as laptop or notebook computers. Unfortunately, the use of such faster and more powerful computer components often results in increased heat generation by such computing devices. Thus, improved heat dissipation technology is often needed to maintain operating temperatures of portable computing devices within the same range as their predecessors or some other acceptable range.
A portable computing device typically includes a base and a screen which are rotatably attached by a hinge. The base usually has an input device such as a keyboard or a touchpad as well as a number of electronic components. Integrated circuits with the highest clock frequency are typically located in close proximity to each other within the computer base.
Many heat generating computer system components take the form of integrated circuits. Such integrated circuits are typically mounted on a motherboard or another circuit board within the base of the portable computer device. A processor is one component that generates a large amount of heat in a typical computing device. Other electrical components which also generate heat include memory circuits, power supply circuits, and circuit boards such as a video card.
Maintaining operating temperatures of computer system components below certain levels is important to ensure performance, reliability, and safety. Most integrated circuits have specified maximum operating temperatures, above which the manufacturer does not recommend operation. Transistors, the building blocks of integrated circuits, tend to slow down as operating temperature increases. Thus, a computer system that operates its integrated circuits close to or beyond recommended timings may fail as temperature increases.
Additionally, integrated circuits may be physically damaged if temperatures elevate beyond those recommended. Such physical damage obviously can impact system reliability. Finally, the computer system casing should be kept at a temperature which is safe for human contact. This may necessitate spreading of heat throughout a computer system base or efficiently expelling heat to avoid hot spots near certain components such as a processor.
Typically, heat sinks, fans, and heat pipes are employed to dissipate heat from integrated circuits and other electronic components. Increases in heat generation are often accommodated by simply increasing the quantity or size of these heat dissipation elements. The relatively small size of a portable computing device, however, complicates heat dissipation by limiting airflow, crowding heat generating components, and reducing the space available for heat dissipation devices.
The small size of a portable computing device particularly restricts the use of cooling fans. As is illustrated in FIG. 1, a prior art cooling fan 150 is typically vertically mounted at an external surface of a portable computing device 105. As illustrated, the fan 150 is mounted in the plane of a side wall 120. This mounting plane is perpendicular to the axis of rotation of a shaft in the motor 160 and the fan blade 155 attached thereto. Air flows perpendicular to the axis of the mounting plane (i.e., parallel to the axis of rotation of the motor shaft and blade).
A side wall 120 of the base of the portable computing device is typically used since the lower surface of the device may be blocked by the surface upon which the device is resting and the upper surface typically houses a keyboard and may be blocked by the display (when the device is closed) or other objects resting on the device. The side or back of a computing device normally remains unobstructed during operation of the device and is accordingly a better candidate for fan mounting.
Since the form factor (the height of the side wall 120 ) of portable computing devices has become quite small and continues to decrease, vertically mounted side wall fans become less effective since their size must be decreased and the motor 160 (unless also shrunk) becomes a larger percentage of the fan area. Generally, such smaller fans are less powerful, have smaller blades, and are generally less effective at cooling the portable computing device.
Thus, the prior art fan cooling arrangements generally provide decreasing cooling capabilities as form factors decrease. Unfortunately, as electronic components use increasing amounts of power, increasing rather than decreasing cooling capabilities are needed to maintain components within a specified range of operating temperatures.